Module 2: Basic Pharmacology of Controlled Drugs and Substances

Lesson 1

Some Basic Definitions (cont’d)

Evidence is growing related to these four pharmacological concepts, demonstrating their importance in understanding client response to controlled drugs and substances, including desired therapeutic outcomes, adverse effects, and addiction. This holds potential for reducing the incidence and prevalence of misuse and addiction when these medications are prescribed.

Three other important concepts to keep in mind are affinity, agonist and antagonist. Affinity refers to a drug’s attraction to a specific receptor site; the higher the affinity, the lower the concentration needed to trigger a response. A drug acts as an agonist when it has an affinity for a receptor and triggers a response.  A drug is said to be an antagonist when it has an affinity for a receptor but does not elicit a response and can actually block the expected effect of the agonist. Antagonists can be used purposefully to block the effects of a substance that is naturally present in the body as well as to block or reverse the effects of other medications, such as naloxone’s effect on opioids (Poole Arcangelo & Petersen, 2016).